1. Field of Invention
The invention relates to devices for measuring the rates of flow of a fluid through a line. More particularly the invention relates to use of bladed radial turbines driven by the fluid at a rate of rotation dependent on the rate of fluid flow. With more particularly the invention relates to turbine flowmeters whose rate of rotation per unit of fluid flow that is, metering characteristics) may be varied so as to accommodate fluids of differing specific gravity and viscosity, or varied to accommodate a wide range of flow velocities. With even more particularity the invention relates to turbine flowmeters whose metering characteristics ("K factor") can be adjusted externally, in situ, without replacement of any parts.
2. Description of Prior Art
In virtually every industrial field there is at least some requirement for measuring the rate, or volume, of fluid which is, or has, flowed through a line or pipe. Numerous means are used to accomplish this task, including, but not necessarily limited to differential pressure meters (such as, orifice plates, venturi tubes, flow tubes, flow nozzles, pitot tubes, elbow meters, target meters, and variable area meters), positive displacement meters (such as, reciprocating piston meters, oval-gear meters, nutating-disk meters and rotary vane meters), velocity meters (such as turbine meters, vortex meters, electromagnetic meters, and ultrasonic meters) and mass flowmeters (such as, coriolis meters, and thermal mass meters).
Turbine flowmeters have found widespread use for accurate fluid measurement applications. The meter generally consists of a multiple-bladed turbine wheel mounted within a pipe perpendicularly to the liquid flow. Fluid passing through the turbine causes it to rotate about its axis. The rotational speed of the turbine is a direct (not squared) function of flow rate and is typically sensed by magnetic pick-up, photoelectric cells or tachometer means. Flow rate totaled for a given period of time is proportional to flow volume.
One example of a turbine flowmeter is disclosed in Owen, U.S. Pat. No. 3,217,539. In said patent the axis of rotation of the turbine is substantially parallel to the fluid flow.
Another turbine flowmeter is disclosed in Dee, U.S. Pat. No. 3,427,879. In said patent the turbine also rotates about an axis which is substantially parallel to the fluid flow.
Stapler, U.S. Pat. No. 4,030,359 relates to a turbine flowmeter probe for measuring fluid flow in open streams or near the discharge of pipes. A turbine is carried within a cylinder, which cylinder can be clamped to a handle at any point within a 90.degree. arc. The purpose of the adjustable clamping head is simply to facilitate alignment of the axis of the turbine t the direction of fluid flow.
Another variation of a turbine flowmeter is disclosed in Cohrs, U.S. Pat. No. 4,102,189. In said patent a turbine shrouded by a cylindrical sleeve is mounted on a probe. A pickoff coil senses the speed of the turbine wheel. If an overspeed condition of the turbine is sensed, the sleeve and turbine is rotated, as a unit, 90.degree. to the direction of fluid flow, thereby preventing bearing damage.
Guthrie, U.S. Pat. No. 4,134,298 describes another probe type turbine contained within a cylindrical sleeve. The turbine wheel is normally located with its axis parallel to the direction of fluid flow, but, in the event of turbine overspeed, the turbine is rotated 90.degree. to the direction of fluid flow to prevent bearing damage.
Amemori, et al, U.S. Pat. No. 4,242,916 discloses a turbine flowmeter for measuring fluids of differing coefficients of viscosity. In said patent the turbine axis is parallel to the direction of fluid flow. Adjustment of the flowmeter to accommodate differing fluids is accomplished by setting the distance between an upstream guide and a downstream guide so as to alter the state of fluid flow impinging on the turbine wheel.
None of the aforesaid inventions disclose an "in line" flowmeter wherein the axis of the turbine is settable throughout a range from a direction parallel to the fluid flow to a direction perpendicular to the fluid flow.
The invention disclosed herein represents a significant improvement over prior art in that the "K factor" (the number of turbine rotations per unit of flow rate or flow volume) of the disclosed flowmeter can be varied, by selecting the appropriate angle between the turbine axis and the direction of flow, to measure fluids of different viscosities and specific gravities, and provide greater rangeability than that possible with a fixed position turbine flowmeter.